Ok, Tried countless times - cloning mac addresses - numerous reboots - resets , etc.
Spoke to ntl BB tech who was very helpful , they ran through the setup procedure with me and then confirmed that the line was fine to my stb but they could not get a signal between stb and router.
There has never been a lit internet light on this router - not even a flicker.
I think its faulty so will get another one.
Thanks for all your help and suggestions.
Iain